linux-kernel - Re: [PATCH 6/7] remoteproc: qcom_q6v5

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Message-ID: <be23b02d-d2b5-2bec-487b-35caf90f29f7@quicinc.com>
Date: Fri, 17 May 2024 12:49:47 +0530
From: Mukesh Ojha <quic_mojha@...cinc.com>
To: Chris Lew <quic_clew@...cinc.com>, Bjorn Andersson <andersson@...nel.org>,
        Baolin Wang <baolin.wang@...ux.alibaba.com>,
        Peter Zijlstra
	<peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
        Will Deacon
	<will@...nel.org>, Waiman Long <longman@...hat.com>,
        Boqun Feng
	<boqun.feng@...il.com>, Jonathan Corbet <corbet@....net>,
        Mathieu Poirier
	<mathieu.poirier@...aro.org>,
        Rob Herring <robh@...nel.org>,
        "Krzysztof
 Kozlowski" <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        Konrad Dybcio
	<konrad.dybcio@...aro.org>
CC: <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-doc@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <devicetree@...r.kernel.org>, Richard Maina <quic_rmaina@...cinc.com>
Subject: Re: [PATCH 6/7] remoteproc: qcom_q6v5_pas: Add hwspinlock bust on
 stop



On 5/17/2024 4:28 AM, Chris Lew wrote:
> From: Richard Maina <quic_rmaina@...cinc.com>
> 
> When remoteproc goes down unexpectedly this results in a state where any
> acquired hwspinlocks will remain locked possibly resulting in deadlock.
> In order to ensure all locks are freed we include a call to
> hwspin_lock_bust() during remoteproc shutdown.
> 
> For qcom_q6v5_pas remoteprocs, each remoteproc has an assigned id that
> is used to take the hwspinlock. Remoteproc should use this id to try and
> bust the lock on remoteproc stop.
> 
> This edge case only occurs with q6v5_pas watchdog crashes. The error
> fatal case has handling to clear the hwspinlock before the error fatal
> interrupt is triggered.
> 
> Signed-off-by: Richard Maina <quic_rmaina@...cinc.com>
> Signed-off-by: Chris Lew <quic_clew@...cinc.com>
> ---
>   drivers/remoteproc/qcom_q6v5_pas.c | 28 ++++++++++++++++++++++++++++
>   1 file changed, 28 insertions(+)
> 
> diff --git a/drivers/remoteproc/qcom_q6v5_pas.c b/drivers/remoteproc/qcom_q6v5_pas.c
> index 54d8005d40a3..57178fcb9aa3 100644
> --- a/drivers/remoteproc/qcom_q6v5_pas.c
> +++ b/drivers/remoteproc/qcom_q6v5_pas.c
> @@ -10,6 +10,7 @@
>   #include <linux/clk.h>
>   #include <linux/delay.h>
>   #include <linux/firmware.h>
> +#include <linux/hwspinlock.h>
>   #include <linux/interrupt.h>
>   #include <linux/kernel.h>
>   #include <linux/module.h>
> @@ -52,6 +53,7 @@ struct adsp_data {
>   	const char *ssr_name;
>   	const char *sysmon_name;
>   	int ssctl_id;
> +	int hwlock_id;
>   
>   	int region_assign_idx;
>   	int region_assign_count;
> @@ -84,6 +86,9 @@ struct qcom_adsp {
>   	bool decrypt_shutdown;
>   	const char *info_name;
>   
> +	struct hwspinlock *hwlock;
> +	int hwlock_id;
> +
>   	const struct firmware *firmware;
>   	const struct firmware *dtb_firmware;
>   
> @@ -399,6 +404,12 @@ static int adsp_stop(struct rproc *rproc)
>   	if (handover)
>   		qcom_pas_handover(&adsp->q6v5);
>   
> +	if (adsp->hwlock) {
> +		ret = hwspin_lock_bust(adsp->hwlock, adsp->hwlock_id);
> +		if (ret)
> +			dev_info(adsp->dev, "failed to bust hwspinlock\n");
> +	}
> +

What if recovery is disabled, fatal case is clearing the hwspinlock but
wdog case is not, right ?

-Mukesh